The invention relates to archery arrows, and more particularly, to inserts for aluminum arrow shafts to receive threaded studs of removable arrowheads, and still more particularly to archery broad blade arrowhead attachment devices that avoid windplaning of arrows in flight.
Modern archery arrows are frequently made of lightweight aluminum or other suitable metal tubing material. Slightly offset feathers or fletching are provided on the trailing end of the shaft to cause rapid spinning of the shaft during flight, as this is known to improve the range, stability and accuracy of arrows. Various kinds of arrowheads are used, including target arrows which have no blades, and various kinds of hunting arrows, which have broad blades. Since the aluminum shafts are expensive, removable arrowheads with threaded studs have been devised and are quite popular. The leading ends of arrow shafts have inserts therein with threaded openings to receive the threaded studs, so an archer can remove a damaged arrowhead and replace it without incurring the expense of buying an entire new arrow, or he can exchange one type of tip for another type, thereby reducing the number of arrows of different types that he needs to own.
Target arrowheads are very streamlined since they have no blades, and do not deleteriously affect the flight of a rapidly spinning arrow. However, broad blade hunting arrowheads have a singificant amount of blade area which interacts with the air currents created while the rapidly spinning arrow is in flight. This effect, referred to as "windplaning", causes an undesirable loss of range and accuracy of the arrow. It should be noted that the above-mentioned interaction of the blade area is aggravated by the manner in which an arrow is propelled by a bow. The shaft of an arrow is always somewhat flexible, and will tend to flex in an oscillatory manner during flight. This oscillatory flexing is initiated by the way that the bowstring is released. As the archer releases the bowstring, it rolls sideways and over the ends of his fingers, thereby also displacing the nock of the arrow sideways. As the bowstring propels the arrow forward, the bowstring naturally also tends to move sideways back to its original plane, but "overshoots" due to the mass of the string and the rear end of the arrow. The handle of the bow, against which the arrow rests, is rigid, so the oscillatory flexing of the arrow shaft is thereby initiated. A large amount of spin of the arrow during flight will tend to reduce the oscillatory flexing, but interaction between air currents, a typical broad blade arrowhead, and feathers or plastic vanes on a shaft can tend to reduce such spinning of the shaft and also increase the amount of windplaning.
Certain prior art devices are known which provide a means for rotationally connecting a broad blade hunting arrowhead to the leading end of a shaft. For example, U.S. Pat. No. 3,910,579 by Sprandell discloses such a device and teaches that the device disclosed therein causes the arrow shaft to rotate at a different rate than the broad blade arrowhead, resulting in truer flight, and prevents the arrowhead from turning at the time that it penetrates the flesh of an animal, thereby resulting in greater penetration of the flesh without torquing or binding of the head or excessive tearing of the flesh. U.S. Pat. No. 4,175,749 by Simo discloses a broad blade arrowhead which rotates with the arrow shaft while in flight, but upon initial penetration of target material, the broad blade portion ceases to rotate relative to the arrow shaft and nose piece to thereby lessen the loss of forward penetration energy from the arrow so that a greater quantity of the arrow's energy is available for forward penetration into the target material.
Unfortunately, none of the above structures provide the low amount of frictional resistance to rotation of the arrowhead needed to adequately reduce the amount of windplaning caused by a broad blade arrowhead.
Therefore, it is an object of the invention to provide an arrowhead, especially a broad blade hunting arrowhead, which rotates much more freely relative to an arrow shaft than prior art devices.
When hunting arrows miss their targets, either targets used for target practice or prey during hunting, the arrowheads often are thrust into dirt or are otherwise exposed. Minute particles of dirt, dust, etc. which enter into the bearing mechanisms of prior rotational arrowhead devices, further increasing the friction of rotation, further preventing them from rotating freely enough to effectively reduce windplaning of the arrow. None of the prior rotational arrowhead devices can be easily disassembled and cleaned.
Therefore, it is an object of the invention to provide an extremely low friction rotational arrowhead which is easily disassembled, cleaned, and re-assembled.
Up to now, no one has provided a broad blade arrowhead that adequately, and reliably avoids the effects of windplaning.
Accordingly, it is an object of the invention to provide an improved archery arrow that avoids windplaning when a broad blade arrowhead is used.
It is another object of the invention to provide a means of attaching a broad blade arrowhead to an arrow shaft in a manner that avoids windplaning of the arrow during flight.
It has been found that typical broad blade hunting arrowheads do not penetrate and animal target nearly as much when the arrow shaft and arrowhead thereon are spinning at the instant the arrowhead strikes the animal as is the case if the arrow shaft and arrowhead are not spinning. This is highly undesirable, since it results in animals being wounded but not quickly killed. Frequently, the animals run away and die slowly and painfully. The above-mentioned loss of accuracy due to windplaning of arrows with broad blade hunting arrowheads also results in animals being wounded but not quickly killed.
Accordingly, it is another object of the invention to provide an improved, accurate broad blade archery arrow that both avoids windplaning and penetrates deeply into an animal target.
It is another object of the invention to provide an improved means of attaching a broad blade arrowhead to an arrow shaft to both avoid windplaning of the arrow during flight and to provide improved penetration into a target.